The present invention relates broadly to apparatus and methods for testing rails, especially rails laid along a roadbed to form a railroad track. More particularly, the present invention is directed to a method and apparatus for testing rails using two linearly disposed rail-traveling vehicles and radio-based voice and data communication for data transfer therebetween to include the transfer of rail defect data acquired by the lead vehicle to the trailing vehicle.
Steel rails, such as those used for railroad tracks which extend in a linear, generally parallel relationship, can develop internal structural defects such as stress fractures and other metallic structural anomalies. Such defects, if left unattended, can cause failure, especially fatigue failure, due to the repetitious loading and unloading of the rails by passing trains. Such rail failures can result in disrupted schedules as well as train derailments.
As a response, it is generally known to periodically test the rails using some form of test system. The common form of rail testing involves ultrasonic technology. Specialized rail traveling vehicles carry ultrasonic transducers which transmit sound into the rails and receive and analyze return echo signals. Certain disruptions in the signal may be interpreted as rail defects and certain types of defects will reflect a characteristic signal such that when the characteristic signal is received, the type of defect may be readily determined. Typically, the transducers are carried on wheels or carriages, which are mounted on rail traveling vehicles such that the wheels are maintained in rail contact. Further, the transducers typically propagate waves at 0.degree., 37.degree. and 70.degree. into the rails. The rail traveling vehicles also carry computers which can receive signals from the transducers, process the signals and interpret signal anomalies as defects and can also locate the defect within the rail. General ultrasonic inspection theory may be reviewed with reference to Norris, U.S. Pat. No. 4,429,576; Pagano et al., U.S. Pat. No. 4,487,071; or Cowan, U.S. Pat. No. 3,415,110. All three patents are referenced for their general teachings regarding ultrasonic rail testing.
Typically, a rail traveling vehicle will carry the transducer system including a computer for data analysis. The vehicle will also typically carry an encoder which includes another rail contact wheel having a signal generating device associated therewith for periodic signals which are related to distance traveled from a predetermined starting point such that the location of the test vehicle may be determined by its displacement from a reference position.
Federal Railroad Administration (FRA) rules provide that if the test vehicle identifies a suspicious location on the track, then the vehicle must stop and personnel must confirm the presence or absence of a defect at that location. Utilizing a single vehicle, the test vehicle would be continually moving down the track, stopping, then reversing to investigate indications identified by the test equipment. The speed at which this can be accomplished limits the amount of track that can be tested in a single day or other predetermined time period. In order to increase the amount of track tested per day, the chase car, or two vehicle system, has been developed. This system employs an additional vehicle, i.e., a second or chase vehicle that follows the test vehicle along the track. The chase vehicle is typically a smaller vehicle than the test vehicle with a minimum amount of equipment carried therein. The test vehicle is configured with a rail inspection system and the chase vehicle is configured for receipt of communication from the test vehicle and is sufficiently equipped to allow personnel to conduct the necessary confirmation.
Currently, data sent from the test vehicle to the chase vehicle is minimalistic and typically involves a form of code to indicate that a defect has been found and a printer which will receive data from the test vehicle indicating where the defect was found. Personnel on the chase car must then use their own test equipment to verify the defect. The problem with this approach is that many of the test vehicle capabilities are not fully realized because the data sent to the chase vehicle is minimal and tests performed by the test vehicle must be reperformed by personnel from the chase vehicle.